Dioxin: Complex molecule, hypothetical fears

Charles Lichon

Published 8:00 pm, Saturday, August 4, 2007

(Authors Note: I write this not only as a health professional with over 30 years experience in the public health profession, but also a lifelong resident of the Tri-County area. After having spent 12 years in a Saginaw parochial school, my college education includes a bachelor in environmental health from Ferris State University and a masters in public health from the University of Michigan, as well as being registered with the State of Michigan as an environmental health specialist (R.S.). I raised my kids in Saginaw, and have three older brothers and numerous relatives who also are lifelong residents of this area. The intent of this two-part series is to give a different perspective of the dioxin issue, utilizing some more common methods to help you understand chemicals and their potential effects on the human body. Part I, featured today, will give you some insight into the world of chemicals and chemical health testing. Part II, published next Sunday issue, will discuss the dioxin issue.)

As a health professional, evaluating a health-related issue, I attempt to deal with as much factual information as possible. This is not always the case, however, in the everyday world, nor is it always employed when special interests or politics are involved. Unfortunately much of this information takes on a spin to meet the needs or desires of the individual, group or organizations, public and private. Personally, I have no vested interest, except that of protecting the publics health.

Take, for instance, the class of synthetic chemicals that are attacked on a regular basis for causing cancer or other maladies in humans. Synthetic chemicals are produced in a laboratory as opposed to natures chemicals that occur naturally in the environment. Rarely do you read about the natural chemicals causing any harm to humans, even though they have the potential to do so.

When we hear of a substance that may cause cancer, what does it mean? One way, and probably the easiest illustration of possible cancer-causing substances and risk, is to look at how research defines it. The EPA elects to base its estimates of toxicity risks as a default (or precautionary) principle; i.e., it is based on high-dose animal experiments, usually in rats. Rats are subjected to very high exposure levels of a chemical daily over the course of their life and the data are then used to assess what can possibly happen to humans at typical environmental exposure, which are often thousands to millions of times less.

This is one reason why we have an absence of human evidence for harmful effects. Other reasons include the possibility that animals dont predict human response, the high doses used to overwhelm normal defense mechanisms that protect the animal, or that a threshold for adverse effects might actually exist. Its not for the lack of trying to find evidence of adverse effects. In addition to animal studies, the federal government as well as private groups have studied a large number of populations of people who have been or might have been exposed to dioxin and other chemicals in the workplace or environment without identifying significant medical findings despite careful examination. As an example, chloracne, which is a skin rash, was found at comparatively high exposures after occupational exposure to dioxin.

Consider natures chemical factory. The cup or two of coffee you may have had for the past many years for instance? Consider that coffee, among other natural compounds, contains benzo pyrene (considered by EPA to be a mutagen and rodent and human carcinogen), benzaldehyde (EPA rodent carcinogen), benzene (rodent and human carcinogen), caffeic acid (EPA rodent carcinogen) and hydrogen peroxide (EPA mutagen and rodent carcinogen). Aflatoxin found in peanut butter and bread is a human and rodent carcinogen. Ethyl alcohol, found in bread, wine and rolls, is also considered a rodent and human carcinogen.

These are just a small sample of the types of natural chemicals found in food and beverages, but of the hundreds or thousands of compounds labeled carcinogens by regulatory agencies, only about 25-30 are recognized as causing cancer in humans. If you want to read more on these, check out the American Council on Science and Health (www.acsh.org).

Contrary to common perception, 99.99 percebt of the chemicals humans ingest are natural. The amount of synthetic pesticide residues in plant foods, for example, are extremely low compared to the amounts of natural "pesticides" produced by plants themselves (i.e., isothiocyanates in celery or cardiac glycosides in potatoes). Of all dietary pesticides that humans eat, 99.99 percent are natural: these are chemicals produced by plants to defend themselves against fungi, insects and other animal predators.

But dont become paranoid about these chemicals, for you would have to consume more than most elephants would consume over a period of years to have any chance of negative effects. And if you look at Americas longevity, it continues to rise as each decade passes. We must be doing something right.

Science and our understanding of it change as we complete new studies and develop new technology, and our government agencies must also change, as new information becomes available. What was acceptable as precaution in the absence of knowledge 30 years ago, for instance, no longer has the same relevance. Not accepting sound science and change is a disservice to not only our valuable industrial base in this state, but to all the community as well. If these same agencies do not change their methods based on sound scientific studies, then our elected officials must intervene.

I hope this simplified introduction gives you some insight into the real world of chemicals. Next issue will address how this all relates to a molecule we call dioxin.

Charles Lichon, R.S., M.P.H. is director of environmental health services for the Midland County Health Department.

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